DON'T BAG, GRASSCYCLE!

i went to the lowes site and happened upon this little tid bit on thatch yous can go there (lowes.com) and read the whole thing but here is the relevent part on the bag or mulch debate.

"Forget those long-held beliefs that grass clipping left on a lawn "smother" the grass underneth or cause thatch build-up. This is not true according to the lawn experts at MTD.
It's been found that thatch is not made up of clipping, but of roots, leaf sheaths, and rhizomes. Grass clpping rapidly decompose in the lawn because they contain very little lignin, the component that resist decomposition. Roots and rhizomes contain higher levels of lignin and are more resistant to decomposition and therefore contribute more to the developement of thatch."

Hope this wasn't to long but i think it would help to explain this to a customer who says they want you to bag to prevent thatch build up.